Recent advancements in surgical techniques and instruments have permitted for incisions of reduced size for a variety of surgical procedures. For example, surgical procedures which only a few years ago required an incision six or seven inches in length are today performed through incisions requiring less than one inch in length. Among other advancements, one type of surgical instrument that has been significant in this regard is the trocar.
In general, a trocar is a sharply pointed surgical tool that is used to create and maintain small, bowl-like incisions in a body cavity. Surgical instruments, including miniaturized optical devices, can be inserted through these small incisions and manipulated to perform surgical procedures within the body cavity without ever exposing the patient's internal organs or structures to the outside environment. By enabling the creation and maintenance of small working holes within a patient's body wall, conventional trocars have greatly contributed to the reduction and size of the incisions required to perform surgical procedures thereby reducing the related complications.
Conventional trocars generally include an obturator and a cannula. An obturator is a small, nail-like structure for penetrating the body wall to create a working channel into the body cavity. The cannula is a tube-like structure which is inserted into the incision made by the obturator to maintain a working channel even after the obturator is removed. In a typical scenario, the obturator and cannula are assembled into a single unit by inserting the obturator within the cannula, and then a combination is used to puncture the body wall. The obturator can then be carefully withdrawn from the cannula without removing the cannula from the body wall. Surgical instruments can be inserted through this cannula to perform an entire surgical procedure within the body cavity.
In many surgical procedures involving trocars, the body cavity is inflated with a nontoxic gas before the trocar is employed to create a working pocket or volume within the patient and to prevent the trocar from penetrating internal organs during insertion. In an appendectomy procedure, for example, a patient's abdomen is inflated with a gas through a veress needle. The obturator is then used to place cannulas in various locations throughout the inflated abdomen to perform the procedure. One such cannula would typically be used to pass a small camera and light into the body cavity so the surgeon could view the operating area within the patient. Other cannulas would be used at other locations to pass surgical instruments into the cavity and remove tissue such as the appendix from the patient.
Maintaining the patient's abdomen in an inflated state throughout this procedure is important. To this end, cannulas are often provided with sealing flap valves that are arranged to prevent gas from escaping from the patient's abdomen after the obturator has been withdrawn. These sealing valves, however, do not prevent gas leakage when the surgical instrument has a diameter that is smaller than the diameter of the cannula seal. Instead gas can easily pass through the gap between the inner walls of the cannula and the outer surface of the surgical instrument to deflate the work area. To prevent such deflation of this type from occurring, physicians often are required to utilize only those instruments whose dimensions closely match those of the cannula. This requirement apparently limits the surgeon's freedom of choice in selecting surgical instruments for the procedure. Thus, while a surgeon's instrument might be preferred by a physician, the physician might nonetheless be forced to use a less preferred, and possibly less effective, tool to perform a procedure to avoid deflating a body cavity.
It is also important for the surgeon to use an assembled obturator and cannula for the particular operation and/or patient. Depending on the body cavity to be explored and the patient undergoing the surgery, the surgical procedures can vary significantly. For example, using an assembled obturator and cannula to puncture the stomach of a baby is quite different than using an assembled obturator and cannula to puncture the stomach of an obese adult. Typically, the procedure for a baby requires that the assembled obturator and cannula be inserted just a short way, enough to pierce a thin stomach wall. Conversely, the same procedure for an obese adult requires that the assembled obturator and cannula be inserted through a relatively thick stomach wall. For such procedures, the conventional obturator and cannula assembly is often too long or too short, thereby making the surgery awkward. For example, when using an obturator and cannula assembly that is too long, the upper end of the assembly extends far above the stomach wall thereby making the assembly unstable.
Accordingly, there is a need for a surgical instrument and procedure that addresses the above-mentioned, and other, problems in the prior art.